Looking to add one onto the patio.

Have you had one before? Generally not too good in a humid climate. Get very wet and sticky. Some very good strong vertical fans though or best of all ceiling fans if you have a suitable ceiling. Makro, Homepro, Du Home etc all have. I would decide on what you want then have a look on Lazada. Usually at least 20% cheaper

I agree with Kenny202’s comment. I’m from Arizona and evaporative coolers work great when the humidity if 30% or less. Since that rarely happens here, good fans will move the damp air and help folks feel cooler, and should save you some money when purchasing compared to an evaporative cooler.

Just buy a fan, thats all an EC will do in this environment. 

Evaporative coolers work exactly like the name suggests. Like when sweat evaporates and cools the skin , so do evaporative coolers evaporate water and cool the air. But like sweat will not cool you down very much when it is very humid, evaporative coolers will not cool you very much in a humid environment such as Thailand. It is a function of how much moisture the air can absorb.In a high humidity environment the air is saturated and does not have the capacity to absorbed much more.